Abstract: In layman terms, DDR is basically the result of designing the data to be processed on both the upward and downward signal slopes, whereas SDR is just a single process per signal slope.87% Rating:

Behind DDR

First, a little background on how AMD and Intel ended up in their current market positions, and the influence this has had on the current state of RAM support.

DDR memory has 184 pins, where as SDRAM has just 168.

The initial reason behind this sudden shift in the PC market towards the Athlon and Duron can be attributed to AMD's lower costs at the time when compared to its primary competitor, Intel.

The Pentium III processor which Intel had on the market at the time of this shift in market share did not appear as leading-edge as the Athlon or the Duron processors. Based on reviews from the web, as well as in the traditional printed medium, the Intel Pentium III and the Celeron processors were found to be slower in certain benchmarks (when compared alongside the same MHz clocked AMD Athlon and its lesser priced Duron).

With these encouraging reviews and strong performance showings, along with the quick acceptance towards its processors from the buying public in a matter of months, AMD was able to gain a very strong following with its processors. This shift was attributed primarily to its aggressively priced products and their very strong performance.

Another reason for Intel's slip in the PC market can be attributed to its own insistence in pushing the technology envelope unto its consumers. This happened whether the customer was willing to accept the latest advancements, or not. Mainly this revolved around a deal Intel had signed with Rambus Ram at the time which basically stated it would develop its chipsets and processors to work alongside Rambus Ram technology exclusively.

This new partnership encountered a few major setbacks. First there was resistance by the general buying public and small businesses due to Rambus's extremely high memory costs. Another incident which really hurt Intel's future share of the marketplace was their i820 chipset.

This chipset which was originally developed to support only RDRAM (Rambus RAM), was found to have a bug in its design when matched with an MTH (Memory Translation Hub), that allowed the use of SDRAM, which would ultimately cause serious data corruption or loss in certain circumstances.

This major technological gaffe coincided with the sudden shortage of higher-clocked CPU's such as the 1.0GHz which Intel made available only to its select few major Tier-1 OEM PC manufacturers (ie. Gateway, Dell, Compaq). This caused a major public relations fiasco for the once solidly-designed CPU/chipset technology firm.

AMD stepped in at the right time with a large and steady supply of its processors. The PC market was ready for faster CPU's and AMD was more than able to produce them in high yields. AMD was able to provide faster clocked processors to the buying public much quicker than its competitor, Intel.

Intel did not have, nor could it produce Pentium III's in large quantities at
the time. This allowed AMD to continue grabbing a larger share of the processor
market that was once owned exclusively by Intel.

Now that AMD was considered a major competitor to Intel in the processor market, VIA a Taiwanese chipset manufacturer developed a much more stable chipset. The less expensive chipset supported AMD cpu's and was able to offer features which Intel's own aging BX chipsets weren't able to provide. Intel's i820 couldn't survive long enough for the general public to purchase or accept: PC100/ PC133 SDRAM; ATA 66/ ATA 100; 4x AGP support.

VIA soon replaced their original AMD-only KX133 chipset, and improved upon its design with the now retired KT133A chipset which supported the Athlon's of the day which ran at 200MHz or 266MHz FSB (Front Side Bus).

As mentioned earlier, AMD wanted to specify a new type of RAM which would provide a higher memory bandwidth when compared to the bandwidth limited SDRAM platform - thus the stage was set for DDR SDRAM to enter.